The present invention relates generally to high-speed connectors, and more particularly, to connectors suitable for use in high-speed data transmission with interstitial ground arrangements between groups of differential signal pairs.
In the field of data transmission, the computer and server industries attempt to constantly increase the speed at which their products can transmit and receive data. Most specifications for these type components now call for minimum speeds of 1 Gigabit per second. Such connectors typically utilize differential signaling, meaning that the signal terminals are arranged in pairs of terminals so as to take advantage of the benefits of differential signaling.
However, with the use of differential signaling certain problems arise. A designer needs to bring multiple grounds into the connector in order to ensure signal isolation. A typical approach to providing the grounds in such a connector would be to utilize a single ground in each differential signal pair. This approach may unduly increase the size of the connector and render it ineffective for its intended application. Also, with the use of separate ground terminals for each differential pair, the total number of circuits that can be supported by the connector depends on the number of terminals the connector is designed to support. Hence, if a connector requires ground terminals for each differential pair, the connector will be longer in size and possibly increase the size of the electronic components with which it is used to the extent where it is undesirable to use from a circuit board real estate perspective
Typically, there is a gap in the interface between the connector and the associated circuit board. It is well-known that such gaps can cause undesirable discontinuities in impedance values at higher frequencies that are used in data transmission.
Additionally, some applications require a differential signal connector that can interconnect a plurality of differential signal circuits on two printed circuit boards that are spaced apart in generally parallel planes, that is, one circuit board is positioned above or below the other circuit board. In such applications, the differential signal connector is interposed between the two circuit boards and the electrical connections therebetween may cause undesired levels of stress to be applied to at least some of the terminals of the connector or to the circuit boards at the connector-circuit board interface.
A need therefore exists for a high speed connector that accommodates differential signals that minimizes impedance discontinuities throughout the connector and at the connector-circuit board interface.
A need also exists for providing a plurality of differential signal pairs through the connector, and at the same time, providing a plurality of ground terminals that separate the differential signal pairs into discrete groups of signal pairs, and which also provide an affinity across the connector to circuit board interface for the differential signal pairs to maintain relatively constant impedance through the connector, especially at the connector to circuit board interface.
A need also exists for a high speed connector of the interposer type that accommodates differential signals. There is also a need for such a connector in which the differential terminal pairs have compliant tail portions to reduce stresses on the terminal pairs and on the circuit boards at the connector-circuit board interface.
The present invention provides connectors of the “docking” and “interposer” styles and terminal assemblies used in such connectors that overcome the aforementioned disadvantages. The present invention provides an interposer type connector for interconnecting a plurality of differential signal circuits between spaced apart circuit boards that overcomes the aforementioned disadvantages.